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LWS TR&T Focus Teams:

Use Inner Heliospheric Observations to Better Constrain Coronal Mass Ejection (CME) and Solar Energetic Particle (SEP) Event Models

Team Chair: O.C. St. Cyr
Next Team Meeting:
October 22-23, 2009, GSFC, Greenbelt, MD
Team-Maintained Web Site:
Team Publications:
Second Progress Report
Team Members:

Chee Ng
Curt de Koning
Neil Sheeley
Jakobus le Roux
Ward Manchester

Target Description: The inner heliosphere remains a frontier that has been minimally explored. Thus far, only the Helios mission and Pioneer Venus Orbiter (PVO) have probed this region in any depth. Yet it is key to understanding what happens to Interplanetary CMEs (ICMEs) and their SEP-accelerating shocks in transit from the Sun to the Earth. Now Messenger and Venus Express are providing some new observations. In conjunction with the Solar TErrestrial RElations Observatory (STEREO), the Wind satellite, the Advanced Composition Explorer (ACE), and SOHO, these make a changing constellation of space weather measurements useful for investigating both the widths and the radial evolution of heliospheric space weather phenomena. Planning is also underway for Solar Orbiter/Sentinels and a Solar Probe mission will finally explore this inner frontier in more detail. These upcoming mission opportunities are best exploited if available measurements are used together with our increased understanding to obtain new insights.

Goals and Measures of Success: The goal is to provide observational validation for inner heliosphere models, as well as updated information for new mission instrumentation and observational strategies. Measures of success for this Focused Science Topic include the ability to predict the evolution of shocks in the inner heliosphere that are inferred from remote sensing close to the Sun and in-situ measurements at Mercury’s orbit and beyond. This will require the characterization of coronal and solar wind properties into ~5-10 Rs where ICME shocks are inferred to form. Observational and theoretical tests that resolve contested issues such as the importance of scattering in energetic particle transport, the mode(s) of acceleration at the shock, and the nature and origin of the heavy ion contributions to energetic particle populations are desirable consequences. Improved diagnostics of the physics of CME ejecta evolution and their solar wind interaction as they travel into the heliosphere, accelerating or decelerating and undergoing distortions as they travel, will aid future forecasting efforts and provide Sun-to-Earth event model constraints.

Types of investigations:
• Retrospective analyses with modern tools and models of solar wind properties,
CME/ICMEs and their SEP events observed during the Helios mission;
• Multispacecraft analyses of events detected at Messenger and Venus Express that
use Sun-to-Earth event models; and
• Analyses of 0.3-1.0 AU suprathermal ions from a SEP event seed particle

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